Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have a networking problem with KVM.

There is only one VM on the server and port speed is 100 megabits per second

But maximum download rate is about 1 megabytes per second and expected to be 10mb.

I use virtio and drivers are installed and loaded into kernel.

I tried other NICs but no change and I use bridge networking on the host.

so how to fix this slow performance?

share|improve this question
Are you using bridged networking or something else? What does iperf show? – Michael Hampton Sep 13 '12 at 14:53
Thanks, yes I setup bridge networking with KVM, what exactly do you want from iperf? – Zim3r Sep 13 '12 at 15:43
up vote 1 down vote accepted

If it's possible, check the link speed on switch. It might be set to 10 Mbit/s (10BASE-T). Try connecting directly to server using cross-over cable. If that also fails, the problem is somewhere in configuration/server performance.

share|improve this answer
Thanks, anyway I'll try to call provider. – Zim3r Sep 13 '12 at 15:43

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.